The mechanical properties of a nanocrystalline Al2O 3/a-Al2O3 composite coating measured by nanoindentation and Brillouin spectroscopy

Francisco García Ferré, Emanuele Bertarelli, Angelica Chiodoni, Davide Carnelli, Dario Gastaldi, Pasquale Vena, Marco G. Beghi, Fabio Di Fonzo

Research output: Contribution to journalArticlepeer-review


In this work, ellipsometry, Brillouin spectroscopy and nanoindentation are combined to assess the mechanical properties of a nanocrystalline Al 2O3/a-Al2O3 composite coating with high accuracy and precision. The nanocomposite is grown by pulsed laser deposition at either room temperature or 600 °C. The adhesive strength is evaluated by nanoscratch tests. In the room temperature process the coating attains an unusual combination of compactness, strong interfacial bonding, moderate stiffness (E = 195 ± 9 GPa and ν = 0.29 ± 0.02) and significant hardness (H = 10 ± 1 GPa), resulting in superior plastic behavior and a relatively high ratio of hardness to elastic modulus (H/E = 0.049). These features are correlated to the nanostructure of the coating, which comprises a regular dispersion of ultrafine crystalline Al2O 3 nanodomains (2-5 nm) in a dense and amorphous alumina matrix, as revealed by transmission electron microscopy. For the coating grown at 600 °C, strong adhesion is also observed, with an increase of stiffness and a significant enhancement of hardness (E = 277 ± 9 GPa, ν = 0.27 ± 0.02 and H = 25 ± 1 GPa), suggesting an outstanding resistance to wear (H/E = 0.091).

Original languageEnglish
Pages (from-to)2662-2670
Number of pages9
JournalActa Materialia
Issue number7
Publication statusPublished - Apr 2013


  • Alumina
  • Coating
  • Mechanical properties
  • Nanocomposite
  • Pulsed laser deposition

ASJC Scopus subject areas

  • Ceramics and Composites
  • Metals and Alloys
  • Polymers and Plastics
  • Electronic, Optical and Magnetic Materials

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